Can Neutron Star Become Black Hole

[Pyrotex]

Wow! Somebody else has read "Dragon's Egg". Excellent!
It is a fantastic novel, and would be still even if the good Dr. Forward were not one of America's premier theoretical physicists, specializing in gravitational theory and modeling. I say that to impress on you that all the "science" in the novel is as close to REAL, UNDERSTOOD science as you could get in the days when the novel was published. It may still be very accurate.

I met Robert Forward once. Very friendly and outgoing guy.

[CraigD]

Originally Posted by Pyrotex

Wow! Somebody else has read "Dragon's Egg". Excellent!

Yeah, “Dragon's Egg” is IMHO a true hard SF classic, which along with most of Forward’s fiction and non-fiction, are among my favorite books.

Originally Posted by Pyrotex

It is a fantastic novel, and would be still even if the good Dr. Forward were not one of America's premier theoretical physicists, specializing in gravitational theory and modeling.

I think its safe to say that Forward ranks high in actual science knowledge among even hard SF writers. He was a bona fide PhD of Physics. However, his life’s work was always focused on the applied, making him I think more of what we’d now call a technologist than a theoretical physicist.

I find his vision of the near-term future of technology one of the most compelling. My own vision of the future of technology is taken nearly verbatim from Forward’s (most of it described in his alternating fiction/nonfiction book “Indistinguishable from Magic”), updated as the future unfolds.

Originally Posted by Pyrotex

I met Robert Forward once. Very friendly and outgoing guy.

I’m envious, having missed the opportunity myself, as Robert Forward died in 2002.

Another hard SF romp concerning neutron stars is Steven Baxter’s “Flux” – though, unfortunately, knowing in advance that it involves a neutron star spoils one of the book’s major plot devices, as read in its original, until 2/3rds or so of the way through, the reader is lead to believe that its characters are biologically normal humans living in a strange world.

The physics of either book, or better still a comparison of both, would make for a good thread.

Important to the real science of neutron stars, though, is to note that in both books, exotic science and technology, and an abundance of luck, is needed for a normal human observer to even detect that the story taking place on the neutron star is occurring. Though the books do a compelling job of speculating that life on a neutron star is possible – and arguable superior in dramatic ways to our low-gravity kind of life – they in no way assure that such life actually exists, or that if it does, we’ll ever be able to detect, (as described in “Dragon’s Egg”) interact with, or, (as described in “Flux”) create it.

[litespeed]

Graig - You wrote: "...Although a very high speed, [.4c] this is still not enough to produce a dramatic mass dilation – a factor of about 1.19, (a 19% increase)..."

It is, however, sufficient to address my original question, paraphrased: "Does this mass dialation increase the grivitation of the total system; or is it a separate effect?"

Bassically, I am thinking about the limits of BH physics. Specifically, their gravitation is so extreme that I wonder about two things:

1) Could light, theoretically, go into orbit someplace near or past the event horizon; after all, it never gets back out.
2) Mass dialation could be so extreme that, at some point, even the BH would not have enough gravitational force to actually crush it into a singularity. [PS - I do not believe infinities of any sort exist in our universe, including singularities. But thats just me.]

[freeztar]

Originally Posted by litespeed

It is, however, sufficient to address my original question, paraphrased: "Does this mass dialation increase the grivitation of the total system; or is it a separate effect?"

Short answer: no
"Mass dilation" is a confusing term, imho. Relativistic mass is a better term, but it is still confusing. Remember that mass and energy are related. So, when we consider "mass dilation" it is really a measure of an increase in energy rather than "gravitational mass". The wiki on mass in SR does a better job of explaining it.

Originally Posted by wiki

The term relativistic mass is also used, and this is the total quantity of energy in a body or system (divided by c2). The relativistic mass (of a body or system of bodies) includes a contribution from the kinetic energy of the body, and is larger the faster the body moves, so unlike the invariant mass, the relativistic mass depends on the observer's frame of reference. However, for given single frames of reference and for closed systems, the relativistic mass is also a conserved quantity.

Because the relativistic mass is proportional to the energy, it has gradually fallen into disuse in among physicists[1]. There is disagreement over whether the concept remains pedagogically useful.[2][3]

1) Could light, theoretically, go into orbit someplace near or past the event horizon; after all, it never gets back out.

No. *Everything* within the event horizon proceeds to the singularity. Well, at least that's what theory predicts. It's impossible to know what exactly is going on inside the event horizon as no information can be extracted. In other words, if we sent a probe across the event horizon, it would have no way of transmitting data back to us.

2) Mass dialation could be so extreme that, at some point, even the BH would not have enough gravitational force to actually crush it into a singularity. [PS - I do not believe infinities of any sort exist in our universe, including singularities. But thats just me.]

Again, mass dilation is a confusing term and I recommend reading up on it. Energy does not increase a body's gravity.

If you are interested in BH, I'd recommend doing a search for that here. There are some nice discussions on BH in this very forum.

[CraigD]

Originally Posted by litespeed

Graig - You wrote: "...Although a very high speed, [.4c] this is still not enough to produce a dramatic mass dilation – a factor of about 1.19, (a 19% increase)..."

It is, however, sufficient to address my original question, paraphrased: "Does this mass dialation increase the grivitation of the total system; or is it a separate effect?"

Yes, mass dilation increases the mass of individual bodies in a system, and thus increases the mass of the total system. For example, if no matter was lost or gained, but the temperature of, say, a planet, were decreased, the speed of its molecules would decrease, their mass dilation decrease, the mass of the entire planet decrease, and the gravitational force exerted by it on a test body of constant mass would decrease. Such a decrease would be very small, and practically, be insignificant compared to its unavoidable gains and losses of matter.

Although the speeds of orbiting and infalling bodies around a neutron star or other dense body are greater than those associated with heat on planets, the increase of mass and resulting gravity due to mass dilation is, I think, similarly insignificant. Compared to the total mass of the central body and its accretion disk, the total mass of infalling bodies accelerated to a high speed is very small, and not significant compared to the mass of new matter accreted from interstellar space, or expelled by outgoing radiation, radiation pressure, and much more energetic, explosive events.

Originally Posted by litespeed

1) Could light, theoretically, go into orbit someplace near or past the event horizon; after all, it never gets back out.

As with many questions I’m unable to even begin to answer rigorously, I’ve dedicated a lot of thought to this question, arriving at a conclusive “maybe – I don’t know”.

If General Relativity is as predictive as experiments to date confirm, I suspect, but am unable to calculate, that such orbits might be short-lived, because the photons or other particles would lose energy through the emission of gravitational waves. Because gravitational waves can in theory escape from within the event horizon of a black hole, this should in principle be detectable, though currently beyond human technological capability.

My main interest in this is due to the possibility of using gravity as optical elements in very large telescopes. For this purpose, it would not be necessary for photons to orbit (outside of the event horizon, as once within, they’re unavailable for detection outside it) a black hole or other compact massive body, but only be significantly deflected by it. Arranged and/or sampled carefully, I suspect that this could be used to gain telescopic data much greater than that currently obtained by present day observations of gravitational lensing. The pinnacle of my speculation in this direction is summarized in the post “an exotic variation” of the thread “Time travel” via a really big reflecting telescope.

Originally Posted by litespeed

2) Mass dialation could be so extreme that, at some point, even the BH would not have enough gravitational force to actually crush it into a singularity. [PS - I do not believe infinities of any sort exist in our universe, including singularities. But thats just me.]

I think it’s important to understand that mainstream physics is by no means certain of the existence of singularities. Rather, my read of it is that most physicist believe that the physics that predicts singularities – the “smooth” classical physics of General Relativity – fail on the scales and energies that exist at the centers of black holes. Unfortunately, the physics that most believe can describe these conditions, quantum particle physics, have yet to compellingly include gravitational interactions, which are so inconsequential on the usual scale of quantum physics, but so important in the case of black hole cores. Thus, one tends to find the best physicist speculating that these conditions are “quantum foam” and similar evocative but vague hints at a description.

My personal hunch is that black hole cores are “quark-gluon seas” different from those of ordinary hadrons (protons, neutrons, etc.) only in consisting of vastly more particles, and being subject to gravitational interactions of which we can scarcely imagine using conventional physics. Until theory can better answer the tremendously difficult questions of quantum gravity, I think guesses and hints are the best anyone will be able to offer on the subject of black hole cores.

Fortunately – or unfortunately, depending on you point of view – reality seems bent on sparing us a great need to know the details black hole cores, as such information is for all practical purposes causally disconnected from everything outside the black hole’s event horizon. Black holes, it appears, are nature’s ultimate black boxes.

[freeztar]

Originally Posted by CraigD

Yes, mass dilation increases the mass of individual bodies in a system, and thus increases the mass of the total system. For example, if no matter was lost or gained, but the temperature of, say, a planet, were decreased, the speed of its molecules would decrease, their mass dilation decrease, the mass of the entire planet decrease, and the gravitational force exerted by it on a test body of constant mass would decrease.

This disagrees with what I posted above and my understanding of "mass dilation". I'm going to go ahead and assume my knowledge is incomplete, rather than your's.

With massive bodies traveling a significant fraction of c, is it not the energy that causes the mass dilation? I understand , but I'm still confused as to how this translates to more gravitation. Does this mean that increased energy itself can cause increased gravitation?

I'm obviously missing something significant here and perhaps I need to ponder this for a bit (and do some more reading). Of course, some further elaboration on your (or anyone else's) part would not go unappreciated.

EDIT: Nevermind, I was being dense (no pun intended). I get it now after doing some reading. Specifically, this helped me:

Originally Posted by wiki

Note further that in accordance with Einstein’s Strong Equivalence Principle (SEP), all forms of mass and energy produce a gravitational field in the same way.[9] So all radiated and transmitted energy retains its mass. Not only does the matter comprising Earth create gravity, but the gravitational field itself has mass, and that mass contributes to the field too.

[Moontanman]

Moderation note: moved this post and its replies to the new thread “A mass dilation “paradox” though experiment”, because they apply to physics in general, not just to neutron stars and black holes

How about this thought experiment, if you had a neutron star that was within 1% of being massive enough to be a black home and you accelerated it to .9999% of the speed of light would it become a black hole? more importantly if it did become a black hole would it stop being a black hole if you decelerated it back to an apparent standstill?

[litespeed]

MoonT

I think a discussion of mass v mass velocity might help in discussion of BH creation. For instance, I have seen nothing that indicates simply adding mass to an existing body ever creates a BH. However, just about everyone agrees a spent star of sufficient mass creates a BH when it colapses.

If this is true, then mass by itself is insufficent to create an 'even horizon'. Instead, a certain amount of mass colapsing at great velocity is required to compress the relevant mass beyond simple accretion. Further, I suspect this high velocity mass colapse has relativistic components that enable an event horizon to form.

Any thoughts?

[Moontanman]

Originally Posted by litespeed

MoonT

I think a discussion of mass v mass velocity might help in discussion of BH creation. For instance, I have seen nothing that indicates simply adding mass to an existing body ever creates a BH. However, just about everyone agrees a spent star of sufficient mass creates a BH when it colapses.

If this is true, then mass by itself is insufficent to create an 'even horizon'. Instead, a certain amount of mass colapsing at great velocity is required to compress the relevant mass beyond simple accretion. Further, I suspect this high velocity mass colapse has relativistic components that enable an event horizon to form.

Any thoughts?

I see no reason to think adding mass to a NS would not create a black hole and no reason the think that great speed in necessary to create the collapse that makes a black hole.

Curious About Astronomy: What happens when you change the mass of a White Dwarf or Neutron Star?

In practice, when a binary dumps material onto a white dwarf, a nova will occur, sending most of the added material back out into space. If a white dwarf does, however, gain enough mass through this process, it will collapse in a supernova type I. The supernova is probably too powerful to leave a neutron star behind; the white dwarf is blown apart. On the other hand, a neutron star which accretes too much mass will indeed collapse into a black hole.

More on the adding mass idea

Compact star - Wikipedia, the free encyclopedia

[Jay-qu]

1) Could light, theoretically, go into orbit someplace near or past the event horizon; after all, it never gets back out.

I distinctly remember that this is not possible. Light can orbit a black hole at exactly 3/2 Schwartzchild radii and no less. Closer to a black hole than this the spacetime curvature is too great.

I have forgotten the mathematical proof, I could dig it up if you think it would do you any good to see it.
J